Generally, a laser marking is formed in the wafer so as to identify wafer.
Referring to FIG. 1, a laser marking 20 is formed at an edge portion of a wafer 10. As a semiconductor device is highly integrated, the number of metal layers also increases. Thus, the depth D of the laser marking 20 increases so as to identify each metal layer even when all processes of forming the metal layers are carried out. When a laser is used to form the laser marking 20, a protrusion 22 is formed as a by-product of forming the laser marking 20 and the height H of the protrusion 22 also increases.
Referring to FIG. 2, after forming the laser marking 20 on the wafer 10, a plurality of trench patterns 40 are formed over an entire area of the wafer 10 except an area ranging from an edge of the wafer 10 to a first distance D1 by using a wafer edge exclusion (WEE) of a trench photo etch process (PEP) of a Damascene process.
Next, a copper film is formed on an entire surface of the wafer 10 to fill the laser marking 20 and each trench region 40.
Then, the copper film 30 disposed from the edge of the wafer 10 to a second distance D2 is removed using an edge bead removal (EBR) process.
An object of the EBR process is to remove a predetermined edge portion of the wafer 10 using chemicals, because several contamination problems are caused by the formation of the copper film 30 at the edge portion of the wafer 10.
However, as illustrated in FIG. 3A, a defect is caused by the protrusion 22 as a by-product of forming the laser marking 20. The defect results from a Cu belt formed by an interval between a trench WEE and EBR in a dual Damascene process. If the trench WEE is smaller than the EBR, an unfilled trench pattern collapses during the planarization process and the collapsed unfilled trench pattern serves as a particle source. Therefore, to prevent this phenomenon, the trench WEE is set to be greater than EBR.
Accordingly, if the Cu belt exists in a region encountering the laser marking 20, a step between the protrusion 22 and the trench pattern 40 increases. Thus, there occurs a problem that the Cu film 30 is peeled off in a planarization process.